Ultra-rare Royal Oaks don’t come much prettier than the electric-blue Yves Klein perpetual. Klein was a French artist who became known for frequent use of an electric blue hue which he later patented under code IKB 191. This Royal Oak perpetual and its electric blue dial seem to have been made in his likeness (though the association is not officially sanctioned). While lovely, the 25820ST is not an especially rare RO. This electric dial variant, however, is.
This 25820 perpetual calendar is the most complicated expression of the Yves Klein dial color from AP. The ultra-thin JLC 920 derived caliber just fits in the 39mm case with days of finishing work and a sapphire display back to crown the achievement. The loud hue is an early example of AP’s experimental and adventurous iterating. The basic Royal Oak was such an icon by the 90s that AP took up an entire decade in subtly shifting and playing with its design constituents. I truly do believe this combination of ultra-thin complication and slightly jarring color represents modern AP to its core.
There are maybe one or two of these that come up for sale every few years. To give you some idea, I see the platinum and salmon-dialed 25820PT more commonly listed at auction. This example comes with an extract but no set. Its dial is in exceptional condition and the case/bracelet are strong. Light marks of use are visible but nothing remotely offensive. All told, it’s a strong example of an ultra-rare variation.
Find this Yves Klein Royal Oak Perpetual here from ACM for 94000 GBP